Shuttle press

ABSTRACT

A press for performing work operations on sheet material and having first and second stations at which such work operations are performed. A shuttle which is part of the press moves back and forth along a predetermined path to index the sheet material through the stations. The press includes a platen and preferably substantially all of the press lies beneath the platen. Although various work operations can be carried out on the press, one of these operations involves impact piercing in which the punch strikes against the sheet material with sufficient velocity to form an aperture therein without entering the die cavity.

United States Patent Vinson 1 July 4, 1972 [54] SHUTTLE PRESS 2,351,399 6/1944 Caracciolo et al. ..83/2l8 X I 1,082,518 12/1913 Hausman ..83/2l8 [72] Orange 2,275,612 3/1942 Chandler ..83/218 x [73] Assignee: Vinson Industries, Inc., Orange, Calif.

Primary Examiner-James M. Meister [22] May 1970 Attorney-Smyth, Roston & Pavitt [21] Appl. No.: 33,592

ABSTRACT 52 us. 01 .33/14, 83/50, 83/218 A Press Perfmming Shea and 83 /25 5 83/621 having first and second stations at which such work operations [51] Int. Cl. "1326f 1/02 are performed A shuttle which is part onhe Press moves back 58 Field of Search ..s3/21s x 255 x 55 685 621 x and Path index Shea 83214 225/1 material through the stations. The press includes a platen and preferably substantially all of the press lies beneath the platen. [56] References Cited Although various work operations can be carried out on the press, one of these operations involves impact piercing in UNITED ES P T N S which the punch strikes against the sheet material with suffi- 1 019 005 2/1912 H 83/218 cient velocity to form an aperture therein without entering the avener 37,189 12/1862 3,522,749 8/1970 Fuchs,.|r.

Westlake ..225/1 die cavity.

17 Claims, 19 Drawing Figures 27 2A Z3 35\ i J 1 1 17 j PATENTEDJUL m 3.671901 I sum 1 or 7 Q & Irma/vi);

srw'rrus PRESS BACKGROUND OF THE INVENTION Many parts are fabricated from sheet material of various kinds such as aluminum, steel, tape, ceramics, etc. The fabrication of the part typically includes progressively and inter mittently feeding thesheet material through several stations of the press with one work operation being performed at each of the stations by appropriate tooling and with the completed part being blanked out at the last station.

It is conventional practice to use automatic feeding mechanisms such as roll or hitch feeds to move the sheet material through the several stations. These feeding mechanisms are not part of the press and are expensive. The typical feed mechanism does not index the sheet material through the stations as accurately as necessary for many precision operations. The feeding mechanism is typically remote from the station at which the work operations are performed and reacts relatively slowly so that the speed of stock feeding consumes a relatively large amount of time.

For example, a roll feed roughly indexes the sheet material and bullet nose pilot punches cooperate with preformed apertures in the sheet material to finally align the sheet material with the tooling. This requires a special work operation to preform the apertures and because of allowable tolerances between the pilot punches and the preformed apertures, the final positioning of the sheet material is not as accurate as is necessary or desirable for many work operations. In addition there is an interval of time when the sheet material is not held in position by the roll feed or the pilot punches.

Many pressesare not accurate notwithstanding the manner of stock feed. The recognition of the factors causing such inaccuracy and their solution form a part of the present invention.

In an effort to increase accuracy, it is customary to employ a die set on the press; While this does improve accuracy, equipment cost and set up time are increased.

SUMMARY OF THE INVENTION The present invention eliminates the problems described above. One aspect of the present invention is to employ a shuttle. which is part of the press itself for feeding the sheet material through the press. The shuttle is closely adjacent the stations of the press at which the work operations are to be performed. The shuttle eliminates the expensive automatic feeding mechanisms used heretofore and provides a much more rapid and accurate feed. Pilot punches and die sets are not necessary with present invention.

The shuttle concept involves the use of one or more shuttle members which are drivingly engageable with the stock to move the stock a distance corresponding to the distance between adjacent work stations. The shuttle can then be returned to its initial position and caused to impart a second increment of movement to the sheet material in the same manner. Operation of the shuttle is appropriately coordinated with the operation of the tooling and the other parts of the press.

Although the shuttle concept can be implemented in different ways, according to the present invention, it is preferred to utilize a portion of the tooling such as a punch to feed the sheet material. With the present invention the punch cooperates with a die at a first station to perform a work operation on the sheet material with the work operation deforming the sheet material to interlock the punch and sheet material.

Thereafter, the punch is moved to a second location which may be a second work station, and the sheet material is indexed accordingly due to the interlock between the punch and the sheet material. The interlock may be obtained, for example, by a piercing operation in which an aperture is pierced in the sheet material and the punch engages the surface which defines the aperture to permit it to index the sheet material. In this instance, the punch and the sheet material are interlocked or drivingly connected, but not in the sense that the punch cannot be withdrawn from the aperture.

However this concept of the invention is not limited to a piercing operation as other work operations such as coining, stretching, etc. can be used to obtain the necessary interlock between the sheet material and the tool. Although the interlock could occur between the punch and preformed apertures in the sheet material, the necessary tolerances between the punch and preformed apertures introduces some inaccuracy. Accordingly, it is preferred to have the punch perform a work operation on the sheet material which results in the interlock. Preferably the work operation is one which is useful in fabricating the part. The interlock can be obtained between the sheet material and many different kinds of tools of which a piercing punch is merely illustrative.

A feature of the present invention which improves the accuracy of the press is that the sheet material is tightly gripped or held throughout the work operations and during indexing of the sheet material with such gripping occurring at locations closely adjacent the work stations. To accomplish this, the present invention provides a secondary pad which holds the sheet material tightly against the die except during indexing of the sheet material. When the sheet material is being indexed, it is interlocked with the punch to thereby prevent misalignment of the sheet material relative to the punch during stock transit. Accordingly, there is virtually no way to introduce inaccuracy into the stock retaining and transporting functions.

The punch is preferably of the type which performs work operations on the sheet material at the first and second stations although other punches or tools could be used. Preferably the punch has a tip portion which performs the work operation at the first station and which transports the stock. The punch also has a second portion of enlarged cross section which performs a work operation at the second station. Such work operations may include, for example, piercing an aperture at the first station and blanking out the part at the second station to thereby form a washer-like element. Another advantage of the two stage punch is that it is merely further advanced to perform the second work operation rather than first being fully retracted.

Although various work operations can be carried out on the press of this invention, one such work operation is impact piercing in which the punch is impacted against the sheet material with sufficient velocity to propel a slug of the material into the die cavity to thereby form an aperture in the sheet material. This process can be carried out even though the punch does not pass completely through the sheet material and therefore does not enter the die cavity. As the punch does not enter the die cavity, wear on the tooling is substantially decreased.

Impact piercing of relatively soft materials such as cloth can advantageously be carried out by trapping a volume of air between the punch and the cloth. As the punch descends, it compresses the air to a high pressure as there is insufi'lcient time for the air to escape. This high pressure which may be coupled with actual impact of the punch against the cloth removes or explodes a slug of the material into the die cavity without the punch entering the die cavity.

Numerous other factors contribute to the speed and accuracy of the press of this invention. For example, substantially all of the press is located at an elevation beneath the platen thereby lowering the center of gravity of the press and tending to stabilize it. The platen is preferably mounted on first and second platen posts which extend downwardly from the platen and which are supported by relatively long bearings. The bearings may have a bearing ratio of the order of 6 to 1. In addition, the platen posts are preferably positioned relative to the punches carried by the platen so that substantially no moment is created about a line drawn between such posts as a result of performance of the work operation. To further improve the speed of the device, the platen and secondary pads are preferably driven by full harmonic cams which are much faster than an eccentric. The cams can be changed to thereby permit programming of the operations performed by the press.

Another feature of this invention is the use of a carriage mounted beneath the platen for movement in a predetemiined direction such as along a path parallel to the plane of the sheet material. The platen is movable with the carriage in such plane and is movable relative to the carriage in a direction generally transverse to such plane. In this manner the platen is made capable of accurate compound movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view through tooling and pads showing the punch in an initial or start position.

FIG. 2 is a sectional view similar to FIG. 1 showing the position of the tooling immediately-following the first stage advance of the punch to perform a piercing operation and during stock transit.

FIG. 3 is a sectional view similar to FIG. 1 after a second stage advance of the punch to perform a blanking operation.

FIG. 4 is a sectional view similar to FIG. 1 following the blanking operation with the punch having been elevated out of the sheet material.

FIG. 5 is a schematic view illustrating one preferred path of travel for the punch.

FIG. 5a is a schematic view similar to FIG. 5 illustrating a modified preferred path of punch travel.

FIG. 6 is a side elevational view partially in section of a preferred form of press which can be utilized to carry out the work operations shown in FIGS. 1-4.

FIG. 7 is a plan view partially in section of the press.

FIG. 7a is a sectional view taken generally along line 7a7a of FIG. 7 illustrating a modification of the present invention in which the vertical movement of the platen can be adjusted.

FIG. 7b is an end elevational view taken generally along line 7b-7b in FIG. 7a.

FIG. 8 is a sectional view taken generally along line 8-8 of FIG. 7.

FIG. 9 is an end elevation partially in section.

FIG. 10 is a side elevational view partially in section of the platen and die plate.

FIG. 1 1 is a plan view of the tool holder.

FIG. 12 is a sectional view taken generally along line 12 12 of FIG. 11.

FIG. 13 is a sectional view taken generally along line 13 13 of FIG. 11.

FIG. 14 is a fragmentary sectional view illustrating one preferred form of punch.

FIG. 15 is a sectional view similar to FIG. 14 illustrating a second preferred form of punch.

FIG. 16 is a sectional view similar to FIG. 12 with the punchholder being in an inverted position and otherwise in position for grinding of the punches.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1-4 illustrate some of the sheet material fabricating concepts of this invention. Although the description is concerned primarily with the performance of two work operations on sheet material to perform a washer-like element, it should be understood that the concepts of this invention can be used for equipment having more than two stations and that the invention is not limited to the fabrication of washer-like articles.

FIG. 1 shows a die 1 1 having spaced die members or cavities 13 and 15 therein and a planar upper surface 17 which, in the embodiment illustrated, is horizontal. The die 11 can be suitably mounted on a press such as the press shown in FIG. 6. The die cavities 13 and 15 have outwardly flared lower end portions and cylindrical upper portions 19 and 21, respectively. The die cavities l3 and 15 are at first and second stations, respectively, and they are preferably in different die sections 22 and 22a to thereby permit the distance between stations to be adjusted.

An elongated strip or roll of sheet material 23 is supported on the upper surface 17 of the die 11. The present invention is not limited to work operations on any particular kind of sheet material and the sheet material may be, for example, aluminum, steel, tape, ceramic, cloth, precious metal, etc. in ribbon, coil or strip form or in separate blanks. Similarly, the work operation s described in FIGS. 1-4 hereof are also applicable to parts which have been previously blanked out and are appropriately fed to the first station, i.e., the die cavity 13; however, it is particularly adapted for high speed precision operations on elongated strips or sheets of material.

The sheet material 23 is held in fixed relationship to the die 11 by a secondary pad 25 which clamps relatively large areas of the sheet material 23 tightly and fimily against the upper surface 17 of the die 11. In the embodiment illustrated, the secondary pad 25 has an opening 26 therein to provide adequate room for a punch 27 and a primary pad 29. For clarity of illustration, only a single punch 27 has been illustrated, it being understood that a larger number of fabrication steps can be accomplished in a given time period if multiple punches such as shown in FIGS. 9-11 are employed. The primary pad 29 moves vertically with the punch 27 and moves relative to the punch as permitted by spring means (not shown in FIGS. 14), all of which can be accomplished in a conventional manner. This is more fully described with reference to FIG. 12.

The punch 27 has a cylindrical tip portion 31 and a second stage portion 33. In the embodiment illustrated, the portions 31 and 33 of the punch are generally cylindrical and have a configuration substantially corresponding to the cross sectional configurations of the portions 19 and 21, respectively, it being understood that the configuration and arrangement of the punch and die can vary depending upon the work operations which are to be carried out. The portions 31 and 33 are coaxial in the embodiment illustrated and define an annular shoulder 35.

The punch 27 passes through an opening 37 in the primary pad 29 which preferably generally corresponds in cross section to the portion 33 of the punch.

In the initial position shown in FIG. 1 the pressure pad 25 tightly clamps the sheet material 23 against the upper surface 17 of the die 11. The punch 27 and the primary pad 29 are slightly above the upper surface of the sheet material 23 with the tip portion of the punch being substantially coaxial with the portion 19 of the die cavity 13. As the punch 27 is advanced toward the die cavity 13, the lower surface of the pressure pad 29 strikes the upper surface of the sheet material 23 to further clamp the sheet material in position. The punch 27 continues its downward movement as permitted by the resilient connection between the punch and the primary pad 29 and ultimately impacts against the upper surface of the sheet material 23 at high velocity.

The tip portion 31 travels at substantial distance through the sheet material 23 without passing completely therethrough. Because of the high velocity of the punch 27, a slug 39 of the sheet material (FIG. 2) is pierced out of the sheet material 23 thereby forming an aperture 41. The tip portion 31 may travel, for example, only percent through the thickness of the sheet material if it is travelling at the proper velocity. Thus, the tip portion 31 does not enter the portion 19 of the die cavity and wear on the punch and die is reduced.

Alternatively, the punch 31 may not be stopped until it passes completely through the sheet material 23 to thereby form the aperture 41 in a conventional manner. During this time, the pressure pads 25 continue to clamp the sheet material 23 against the upper surface 17 of the die 11.

If the piercing operation is to be of the impact type where the tip portion 31 does not pass completely through the sheet material 23, it is necessary that the punch 27 be travelling at high velocity at the moment it impacts against the sheet material 23. In addition, it is helpful if the sheet material 23 has a relatively brittle quality. Material such as silicon steel, for example, can be impact pierced.

At the completion of the piercing operation which forms the aperture 41, the secondary pads 25 are raised (FIG. 2) and the punch 27 is moved laterally or horizontally toward the die cavity 15. Such movement of the punch 27 occurs without withdrawing the tip portion 31 from the aperture 41 and accordingly the tip portion is interlocked with the sheet material to the extent that it can cause the sheet material to move with the punch to the portion 21 of the die cavity 15. During transport of the sheet material 23, the pressure pad 29 bears against the sheet material 23 so that the movement thereof is resisted to some degree by the force of friction between the sheet material and the surface 17. If desired the sheet material 23 may be guided between stations by lateral guide members (not shown) which engage the longitudinal edges of the sheet material.

When the die cavity is reached, the secondary pad moves downwardly to clamp the sheet material 23 against the surface 17 as described hereinabove. The punch 27 is then further advanced (FIG. 3) to cause the second stage portion 33 thereof to cooperate with the portion 21 of the die cavity 15 to blank out a washer-like element 43 which in the embodiment illustrated is an annular member. The element 43 can be blanked out by an impact process in which the second stage portion 33 does not pass completely through the sheet material 23 and does not enter the die cavity 15. This impact operation can be carried out to blank out the member 43 as described hereinabove to form the aperture 41. During the blanking operation shown in FIG. 3, the primary pad 29 and the secondary pad 25 both clamp the sheet material 23 against the surface 17 of the die 11.

With the secondary pad 25 continuing to clamp the sheet material 23 against the surface 17 of the die 11, the punch 27 is elevated to the position shown in FIG. 4 with such elevation being sufficient to raise the primary pad 29 above the upper surface of the sheet material 23. The punch 27 and the primary pad 29 are then returned to the initial position illustrated in FIG. 1.

As shown in FIGS. 1-4, the secondary pad 25 moves vertically but not horizontally while the punch 27 moves both vertically and horizontally. FIG. 5 illustrates diagrammatically one preferred path of movement of the punch 27. As shown in FIG. 5, the punch 27 begins at an initial position A (FIG. 1) and travels downwardly to position B to pierce the aperture 41 (FIG. 2). The punch 27 then travels horizontally to a position C in which it is aligned with the die cavity 15 and during such horizontal movement, the punch moves the sheet material 23 a distance corresponding to the distance between centers of the die cavities 13 and 15. Next, the punch 27 moves downwardly to position D which is shown in FIG. 3 in which it blanks out the washer-like elements 43. Subsequently, the punch 27 is withdrawn vertically to position E whereupon it returns horizontally to the initial portion A.

FIG. 5a shows an alternate path of movement for the punch 27 which is identical to that described in FIG. 5 except that following the piercing of the aperture 41 at position B, the punch is moved vertically upwardly slightly to a position 13' and thereafter the path of movement is the same as that described with reference to FIG. 5. In position B in FIG. 5a, the tip portion 31 has passed completely through the sheet material 23 and entered the die cavity 13. In this event, it is necessary to withdraw the tip portion 31 sufficiently so that it clears the die cavity 13 but insufliciently to withdraw it from the aperture 41 and this latter position is designated B.

The impact piercing operation shown in FIGS. 1-4 can be assisted or carried out by providing close tolerances between the walls of the opening 37 and the periphery of the punch 27. Thus, when the primary pad 29 bears against the upper surface of the sheet material 23, a relatively tightly enclosed void space is defined by the sheet material 23, the wall of the opening 37 and the lower face of the punch 27. As the tip portion 31 descends toward the die cavity 13, this void space is rapidly and progressively decreased in volume thereby compressing the air which is trapped within such space. Because of the tight tolerances on the punch 27 and the opening 37 and because of the rapid movement of the punch 27, the air cannot escape at a rate which would allow substantial lessening of this air compression action. Depending upon the type of material and the amount of air compression obtained, this air compression effect can be used alone or in combination with the impact of the tip portion 31 against the sheet material 23 to remove the slug 39. The compression of the air results in an explosive or semi-explosive removal of the slug 39. It should be understood that FIGS. 14 are not to scale and that the tooling and the primary pad 29 can be appropriately configured and dimensioned so as to provide varying amounts of air compression during the downward stroke of the punch 27.

FIGS. 6-9 show a press 45 which is capable of accurate, high speed operation. The press 45 is particularly adapted for minature stampings, precious metal stampings, high speed perforation, coining and the work operations described hereinabove with reference to FIGS. 1-4. Of course other presses can be used to carry out the operations described with reference to FIGS. 1-4.

The press 45 includes a base 47 adapted to rest on a supporting surface (not shown, an upstanding peripheral wall 49 having opposed thickened regions defining support members 51 and 53 (FIG. 9), and a top wall 55 (FIGS. 6 and 8).

As shown in FIGS. 7 and 8, the peripheral wall 49 has an opening therein and a bearing support 57 is mounted on the base 47 within such opening. The bearing support 57 supports roller bearings 59 and 61 in coaxial relationship. The bearings 59 and 61 have inner rings 63 and 65, respectively, and a tubular drive shaft 67 is suitably connected to the inner rings 63 and 65 for rotation therewith. A shaft 69 having an enlarged end portion 71 is received in the hollow drive shaft 67 and is affixed thereto by a key 73 (FIG. 6). The key 73 causes the shaft 69 to rotate with the drive shaft 67, but permits relative axial movement therebetween and thus the key 73 acts like a spline. A hand wheel 75, which also serves as a flywheel is affixed to the shafl 69 by a screw 79 and a shoulder 81.

With further reference to FIGS. 7 and 8, an electric motor 83 drives the drive shaft 67 through a gear box 85, a stub shaft 87 and a splined coupling 89. The splined coupling 89 includes a driving member 91 and a driven member 93 with the latter being suitably rigidly connected to the drive shaft 67. The driving member 91 is suitably mounted on the stub shaft 87 for rotation therewith and so as to permit relative axial movement therebetween and such connection may be formed by splines if desired. The members 91 and 93 have cooperating teeth or splines 95 on the cooperating confronting end faces thereof to thereby drivingly connect the members 91 and 93. A spring 97 acts between the member 91 and the gear box to urge the teeth of the members 91 and 93 into driving relationship. The enlarged end portion 71 of the shaft 69 is mounted within the member 93 with the end face thereof being engageable with the driving member 91.

From the foregoing it will be apparent that the motor 85 drives the drive shaft 67 through the gear box 85, the driving member 91 and the driven member 93. Similarly, the shaft 69 rotates with the drive shaft 67 because of the key 73 drivingly interconnecting these two shafts. The hand wheel 75 rotates with the shaft 69 and serves as a flywheel.

In addition, with the motor 83 turned off the hand wheel 75 may be used to facilitate start up of the press. To accomplish this, the hand wheel 75 is urged radially inwardly to thereby force the end portion 71 of the shaft 69 against the driving member 91 to thereby urge the latter axially away from the drive member 93 against the biasing force of the spring 97. This separates the splines 95 and breaks the driving connection between the motor 83 and the drive shaft 67 and allows rotation of the drive shaft 67 by the hand wheel 75.

A pair of earns 99 and 101 are mounted on the drive shaft 67 for rotation with the drive shaft as shown in FIGS. 6-8. The cam 99 has an internal cam surface or track 103. The cam 101 has an external cam surface 105 and an internal cam surface or track 107. The earns 99 and 101 are suitably afiixed to the drive shaft 67 for rotation therewith as by a key 106 (FIG. 6) and are retained thereon by a nut 109 and a washer 111 (FIG. 8). Thus, the earns 99 and 101 can be easily changed by merely removing the nut 109. Although the contours of the cam surfaces 103, 105 and 107 can be varied depending upon the results desired, in the embodiment illustrated the cam surfaces are not eccentrics but are harmonic cams.

The manner in which the cams 99 and 101 are used to produce useful output motion can be best seen in FIGS. 6, 7 and 9. A strong vertical support member 113 (FIG. 6) is rigidly mounted on the base 47 and has a secondary pad arm 115 and a platen arm 117 suitably pivotally connected thereto by shafts 119 and 121, respectively. The vertical support member 113 also rigidly mounts two sleeve bearings 123 (FIG. 7). The sleeve bearings 123 support a pair of platen arms 125 and 127, respectively. The platen arms 125 and 127 are slidable horizontally in the bearings 123. The arms 115 and 117 carry roller followers 129 and 131, respectively. As shown in FIGS. 7 and 8, the follower 131 can be aflixed to the end of the arm 117 in any suitable manner such as by a threaded member 133.

The platen arms 125 and 127 are interconnected by a block member 135 (FIGS. 6 and 7) which carries a cam follower 137. In the embodiment illustrated, the cam follower 137 is in the form of a roller.

The press 45 has a strong horizontal support member 139 which is supported by the vertical support member 113, support members 51 and 53 and another vertical support member 141 (FIGS. 6, 7 and 9). A die or die plate 143 is suitably mounted on the upper face of the member 141 and a secondary pad 145 lies above the die 143 for the purpose of clamping sheet material 147 against the die.

The function of the cam surface 105 and of the arm 115 is to control the vertical movement of the secondary pad 145, the secondary pad being incapable of horizontal movement in the embodiment illustrated. To accomplish this, the arm 115 has a yoke 148 on the opposite end of the pivot shaft 1 19 from the follower 129 which controls the vertical movement of a vertical shaft 149 as shown in FIGS. 6 and 9. The shaft 149 has a bearing 150 at the lower end thereof which rests on bearing elements 150a which in turn are pivotally connected to arms of the yoke 148. Thus, the yoke 148 provides a support for the shaft 149. The upper end of the shaft 149 is rigidly connected to a spring pad bolster 151 in any suitable manner. The spring pad bolster 151 lies beneath the horizontal support member 139 and is spring biased downwardly by springs 153 (FIG. 9) to thereby maintain the follower 129 against the cam surface 105. Four rods 155 (FIGS. 6 and 9) are rigidly mounted in a rectangular pattern on the spring pad bolster 151 and project upwardly through the horizontal support member 139 with the upper ends of these rods being affixed to the secondary pad 145. It can be seen therefore that any vertical motion imparted to the cam follower 129 by the cam surface 105 causes pivotal movement of the arm 115 about the shaft 119 which in turn causes vertical movement of the shaft 149, the spring pad bolster 151, the rods 155 and the secondary pad 145.

The press 45 also includes a platen 159 and a primary pad 160 both of which may take the form shown, for example, in FIG. 10. The platen 159 carries some of the tooling for performing work operations on the sheet material 147, such tooling consisting, for example, of one or more punches. According to the illustrated form of the present invention, the platen 159 is movable vertically by the platen arm 117 and horizontally by the platen arms 125 and 127.

The platen 159 is supported by two platen posts 161 and 163 which are rigidly affixed to the platen and which extend vertically downwardly therefrom. No die set is provided. The posts 161 and 163 pass through sleeve bearings 165 and 167, respectively, which are supported by a horizontally movable block member or carriage 169. The block member 169 is in turn supported on and rigidly affixed to the platen arms 125 and 127 for generally horizontal movement therewith. The outer ends of the platen arms 125 and 127 are slidably receivable in bearings 171 which are mounted on the vertical support member 141. Thus, the platen 159 moves horizontally with the carriage 169 and vertically relative to the carriage.

To assure accurate movement of the platen 159, the bearings 165 and 167 are elongated in the direction of the posts 161 and 163. Preferably the bearings 165 and 167 have large bearing ratios, i.e., the ratio of the bearing length to the diameter of the associated platen post, and the ratio for these bearings is preferably of the order of 6 to l.

The lower ends of the posts 161 and 163 are suitably rigidly affixed to members 173 and 175, respectively. Pins 177 and 179 connect the members 173 and 175 to two keys or shafts 181 of generally rectangular cross section as shown in FIG. 6 with the shafts 181 being pivotable on the pins 177 and 179, respectively. The end of the arm 1 l7 remote from the follower 131 forms a pair of yokes 183 which slidably embrace opposed faces of the rectangular shafts 181, respectively, as shown in FIG. 6. A face plate 185 interconnects the members 173 and 175 to help prevent relative movement therebetween. Any vertical motion imparted to the follower 131 by the cam surface 103 pivots the am 117 about the shaft 121 to thereby impart vertical movement to the platen 159 through the shafts 181, the members 173 and 175, and the platen posts 161 and 163. As shown in FIG. 9, the square shafts 181 and the yokes 183 are spaced apart to provide ample room for the shaft 149 during operation of the press 45.

The platen 159 is moved horizontally by the platen arms and 127. The block member 169 (FIGS. 6 and 9) is suitably affixed to the rods 125 and 127 for horizontal movement therewith as by one or more set screws 187. Horizontal movement of the block 169 moves the bearings 165 and 167 to thereby move the posts 161 and 163 and the platen 159 horizontally. The horizontal support member 139 has a slot 189 (FIG. 6) for each of the platen posts 161 and 163 to thereby permit such horizontal movement of the platen posts to occur. Similarly, the sliding connection between the yokes 183 and the square shafts 181 is suficient to allow the necessary horizontal movement of the square shafts 181 relative to the yokes 183. Accordingly, the cam smface 107 controls the horizontal position of the platen 159. 1

As the press 45 allows the platen 159 to move both vertically and horizontally and causes the pads to move vertically, it is apparent that the work operations described hereinabove with reference to FIGS. 1-4 as well as other work operations can be carried out on the press 45 by appropriate selection of the cam surfaces 103, 105 and 107. In order to position the platen 159 and the secondary pad 145 at the initial position, the hand wheel 75 is used. By urging the hand wheel 75 axially inwardly, the driving connection between the motor 83 and the hand wheel is disconnected to thereby allow manual movement of the components of the press 45 for start up purposes.

Specifically, with reference to FIGS. 5 and 6, the cam surface 103 pivots the platen arm 117 to rapidly move the platen 159 downwardly as represented by the movement from point A to point B in FIG. 5. During this time, the secondary pad 145 tightly holds the sheet material 147 against the upper face of the die 143, the holding force being supplied by the springs 153 (FIG. 9). Also during this time the primary pad holds the sheet material against the die 143. The cam surfaces 105 and 107 dwell and impart no pivotal movement to the arms 1 17 and 135.

During the movement from point A to point B, the tools carried by the platen 159 perform a work operation on the sheet material 147 and following such work operation, the earn 105 raises the secondary pad 145 and the cam surface 107 imparts horizontal movement to the platen 159 as represented by the movement from points B to C in FIG. 5 during which time the cam surfaces 103 and 105 impart no movement to their respective arms. Movement of the platen through points D, E. and A represented in FIG. 5 are accomplished in a similar manner and raising and lowering of the secondary pads 145 can be accomplished by the cam 105 in the sequence described hereinabove with reference to FIGS. 14. Similarly, the movement from B to B illustrated in FIG. 50 can be accomplished by merely making some minor changes in the cam surface 103. Of course, the movements of the secondary pads 145 and the platen 159 described herein are merely illustrative. For example, the press 45 may have more than two stations in which event the platen would be moved to a third station by the cam 107.

FIGS. 7a and 7b show a modification of the present invention which permits adjusting the vertical movement of the platen 159. Except as specifically noted herein, all portions of the press not otherwise referred to in connection with FIGS. 7a and 7b are identical to the press construction described hereinabove. Corresponding parts in FIGS. 7a, 7b and 6-9 are designated by corresponding reference characters followed by the letter a.

As shown in FIG. 7a, the roller 131a is mounted for rotation on a stub shaft 191 and rolls within the cam track 103a of the cam 99a. The stub shaft 191 is received within a cylindrical passage 192 of an eccentric bushing 193. The bushing 193 is in turn retained within a cylindrical aperture 194 of the arm 117a. As shown in FIG. 7b, the bushing 193 is eccentric in the sense that the cylindrical passage 192 is not coaxial with the cylindrical surface of the bushing. A slot 195 (FIG. 7b) extends from the outer surface of the arm 117a inwardly to the opening 194. A lock knob 196 has a stern portion which is threadedly received within a threaded bore 197 of the arm 1170. Accordingly, by turning of the lock knob 196, the circumferential dimension of the opening 194 can be reduced to thereby cause the arm 1 17a to tightly clamp and retain the eccentric bushing 193 in any preselected angular position.

An eccentric adjustment knob 198 is connected to the eccentric bushing 193 by a plurality of screws 199. Thus, with the lock knob 196 loosened to permit rotation of the eccentric bushing 193, turning of the eccentric adjustment knob 198 rotatesthe eccentric bushing 193. As best seen in FIG. 7b, rotational movement of the eccentric bushing 193 displaces the stub shaft 191 and hence the roller 131a. Displacement of the roller 131a results in corresponding pivotal movement of the arm 117 (FIG. 6) to thereby control, within limits, the starting and stopping of the vertical stroke of the platen 159.

In actual practice it is difficult or impossible to make the surfaces of the yokes 183 which slidably engage the shafts 181 precisely parallel to the desired path of the horizontal movement of the platen 159 although these surfaces can be made parallel to each other. However, by appropriately adjusting the knob 198 with the cam surface 103 in dwell position, the arm 117 can be pivoted to make these yoke surfaces parallel to the horizontal path of movement of the platen 159 to thereby assure that these yoke surfaces will not impart vertical movement to the platen during horizontal transfer thereof.

As shown in FIG. 10, the platen 159 has a bore containing a spring 201 and the head 203 of a stripper bolt 205. The platen 159 is rigidly and removably connected at its lower end to a punchholder 207 with the punch holder having a passage therethrough for receiving the shank of the stripper bolt 205. The stripper bolt 205 is connected at its lower end to the primary pad 160. With this construction, it is apparent that the primary pad 160 will travel downwardly with the platen 159 until it engages the sheet material 147 which is supported on the upper surface of the die 143. Thereafter, further downward movement of the platen 159 results in compression of the spring 201 with the consequent application of pressure to the sheet material 147 by the primary pad 160. This construction may be utilized, if desired, in connection with implementing the concept shown in FIGS. 1-4.

The punchholder 207 carries a plurality of punches 209 which extend through the primary pad 160. The die 143 has a plurality of die cavities 211 for cooperation with the punches 209.

The details of the punchholder 207 can best be seen in FIGS. 11-13, it being understood that other types of punchholders can be used with the press 45 of this invention and to carry out the concepts described with reference to FIGS. 1-4. The punchholder 207 includes a body 213 having a bottom wall 214 and side walls 214a and 214b to thereby give the body a generally channel-shaped cross section as shown in FIG. 12. A plurality of screws 215 mounts an inner plate 217 in the body 213 with the screw rigidly affixing the plate to the body. An intermediate plate 219 is connected to a cover plate 221 by a plurality of screws 223. The cover plate 221 has an upper face 225 and the upper end of the head of the screws 223 lies below the face 225 as shown in FIG. 12. The cover plate 221 and the intermediate plate 219 are retained within the body 213 by the platen 159 which bears against the face 225. The platen 159 is secured to the body 213 by a plurality of screws 226 (only one being shown in FIG. 12).

As shown in FIGS. 12 and 13, the body 213 and the plate 217 cooperate to define a chamber 227, access to which is provided by a port 229 in the plate 217. Similarly, the plates 219 and 221 cooperate to define a second chamber 231 access to which is provided by a port 233 and the plate 221.

A plurality of the punches 209 are mounted on the punchholder 207 and in the embodiment illustrated two longitudinally extending rows of the punches are provided, it being understood that the punches 209 can be provided in any number or pattern desired. Preferably the punches 209 are symmetrical about a line drawn between the center lines of the platen posts 161 and 163 so that no moment is exerted on the platen as a result of the work operation.

The details of the punches 209 can best be seen in FIG. 14, it being understood that these punches or other tooling may be utilized to carry out the concepts described with reference to FIGS. 1-4, and conversely, these punches are not limited to use in implementing the concepts of FIGS. l-4. Although the punch 209 could be a one piece member, in the embodiment shown, it includes inner and outer telescoping members 235 and 237, respectively, with the member 237 including a tube 239 and an enlarged head 241 which receives the tube 239 and is suitably afiixed thereto as by braze material 243. As shown, an end portion 245 of the tube 239 projects upwardly above the upper surface of the head 241. The punch 209 can be constructed of any suitable material such as tool grade steel, tungsten carbide, etc. The tube 239 terminates downwardly in an annular working face 247.

The member 235 includes a stern 249 slidably receivable in the tube 239 and an enlarged head 251. In the embodiment i1- lustrated, the tube 239 is cylindrical and the stem 249 is cylindrical; however, other configurations may be utilized if desired. A lower end portion or tip portion 253 of the stern 249 projects downwardly beneath the working face 247 to define a circular working face 255.

The members 235 and 237 are maintained in this position by the punchholder 207 as shown in FIGS. 12 and 14. The head 251 of each of the punches 209 is supported on a lower surface 257 of the plate 219 and the heads 24] are supported on a lower surface 259 of the body 213. The heads 24] and 251 are held in position by matrices 261 and 263, respectively, of a low melting point alloy of the type which melts, for example, in the range from about F. to about 285 F. Such low melting point alloys are known and are available, for example, under the Cerro-lo, Cerro-tru, Cerro-bend and Cerro-matrix. Such material can be cast in situ in the punchholder 207 during assembly of the punchholder. The ports 229 and 233 serve as openings through which the low melting point alloy may be poured. The matrices 261 and 263 hold the punches 209 firmly in position. The enlarged heads 241 and 251 provide additional area for contact by the matrices 261 and 263 to thereby assure that the punches will not move.

The plates 219 and 217 and the lower wall of the body 213 contain appropriate bores to slidably accommodate the adjacent portions of the punches 209 as shown in FIGS. 12 and 14. Specifically, the body 213 includes bores 265 and the plate 217 includes counterbores 267 for receiving longitudinally spaced regions of the tube 239. The bores 265 and the counterbores 267 are of larger diameter than the tube 239 to provide space for moving the punches 209 to accommodate the die. With the punches 209 properly positioned relative to the die, the matrices 261 and 263 are cast in situ and when solidified they prevent movement of the head portions 241 and 251 any direction. In addition, the counterbores 267 provide space for the upper ends of the end portions 245 to prevent the material of the matrix 261 when in a liquid state from entering the tube 239.

The upper end of each of the side walls 214a and 2l4b of the body 213 is defined by horizontal surfaces 271 and 273 separated by a vertical shoulder 275. The shoulders 275 and a dowel pin (not shown) orient the punchholder 207 and the platen 159. One feature of the punchholder 207 is that the vertical dimension X of the shoulder 275 can be selected so that it corresponds to the desired amount that the tip portion 253 of the stem 249 projects downwardly beneath the annular working face 247. Accordingly, in FIG. 12 these two dimensions are substantially equal and are designated with the letter X.

During use of the tooling, the working faces 247 and 255 become worn and need to be reground. One advantage of this construction is during regrinding of the members 235 and 237 of the punch 209. For regrinding, the punchholder 213 can be removed from the platen 159 by removing the screws 226 and inverted on a magnetic chuck 277 or other suitable horizontal surface as shown in FIG. 16. As the platen 159 is the only element holding the plate 219 against the upper surface of the plate 217, the plate 219 is free to move downwardly until the face 225 of the cover plate 221 contacts the magnetic chuck 277. The screws 215, however, holds the plate 217 tightly in position against the body 213. Accordingly, the plate 219 moves relative to the plate 217 to define a gap 279 therebetween. The vertical dimension of the gap 279 is equal to the X dimension shown in FIG. 12. With the punchholder 207 arranged as shown in FIG. 16, the working faces 247 and 255 are approximately flushed. Accordingly, these faces can be rapidly and simultaneously ground until they are flush and have the desired contour.

Upon completion of the grinding operation, the punchholder 207 is again inverted so that it is in the position shown in FIG. 12 and it is reattached to the platen 159. With this arrangement, the punches 209 can be rapidly ground without the need for any special fixtures or without the need for disassembling the punchholder. Thus, the punchholder 207 in essence embodies the necessary grinding fixture and does so in a manner which completely eliminates operator error.

FIG. 15 illustrates a punch 209a which is identical to the punch 209 in every manner not expressly noted herein. Similarly, the punch 209a can be mounted in a punchholder 207a which is identical to the punchholder 207 in every way not specifically noted herein. Parts of FIG. 15 corresponding to parts of FIG. 14 are designated by corresponding reference numerals followed by the letter a.

In the punch 209a, the head 241a has a tubular extension 281 which projects upwardly and terminates flush with the upper end of the tube 239a. The extension 281 reinforces the end portion 2450 of the tube 239a. In order to accommodate the extension 281, the counterbore 267a is of correspondingly larger diameter than the counterbore 267 (FIG. 14).

Also in the form shown in FIG. 15, the braze material 243a is located at the lower end of the head 241a. In all other respects, the punch 209a and its manner of afiixation to the punchholder 207a is identical to that described in connection with FIG. 14.

Although exemplary embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

I claim:

1. A method of performing work operations on sheet material comprising:

providing a first die member at a station;

holding the sheet material with at least a first section of the sheet material being at said first station;

relatively advancing a tool and said first die member to perform a first work operation on said first section of sheet material with the first work operation causing the tool to become interlocked with the first section of sheet materireleasing the sheet material so that the first section can be moved away from the first station;

moving the tool away from the first station to a predetermined location to thereby transfer said first section of sheet material from the first station to the predetermined location and to bring a second section of the sheet material to said first station;

said tool including a punch and said step of relatively advancing causing the punch to enter said first section of sheet material and cooperate with said first die member to pierce an aperture in the first section of sheet material, said punch cooperating with the surface of the sheet material defining said aperture to transfer said section of sheet material to the predetermined location during said step of moving; and

providing a second die member at said predetermined location, said punch having a first portion of a predetermined cross sectional area and a second portion of greater cross sectional area, said first and second portions being cooperable with said first and second die members, respectively, said second die member and said second portion of said punch blanking out said first section of sheet material to thereby form an apertured member of sheet material.

2. A method as defined in claim 1 including relatively advancing said punch and die with sufiicient speed to pierce an aperture in said first section of said sheet material without causing the punch to enter said die member.

3. A method of fabricating an apertured member from sheet material comprising:

providing first and second stations;

providing a first tool at said first station;

holding the sheet material with at least a portion thereof being generally in registry with said first tool;

relatively advancing a second tool and said first tool in direction generally transverse to the plane of the sheet material at said first station to cause said tools to deform the sheet material into interlocking engagement with the second tool;

moving the second tool from said first station to said second station with the second tool moving the sheet material therewith;

performing a second work operation on the sheet material at said second station;

withdrawing said second tool from its interlocking association with the sheet material; and

returning the second tool to the first station.

4. A method as defined in claim 3 wherein said second work operation is carried out utilizing said second tool.

5. A machine for performing work operations on sheet material comprising:

a supporting structure;

a die on said supporting structure and having first and second die cavities at first and second stations, respectively, the sheet material being positionable to confront the die cavities;

a punch having a tip portion and a second portion;

means including a punchholder for mounting said punch for movement toward and away from said die and in both directions between said stations;

means including a pad mounted for movement generally toward and away from the sheet material for clamping the sheet material;

means for moving said pad to effect clamping of the sheet material;

means for moving said punchholder and said punch toward said first die cavity with the tip portion of the punch engaging the sheet material to perform a first work operation thereon, the tip portion of the punch entering the sheet material and interlocking therewith; means for moving the pad away from the sheet material to thereby release the sheet material for movement with said punch when the punch is interlocked with the sheet material; means for moving the punchholder and the punch from said first station to said second station with the punch interlocked with the sheet material to thereby move a section of the sheet material from the first station to the second station and to generally align the punch with the second die cavity; means for moving the pad toward the sheet material to clamp the sheet material when the punch is at said second station; means for advancing the punch toward said second die cavity to cause the second portion of the punch to cooperate with the second die cavity and perform a second work operation on the sheet material; means for moving the punchholder to withdraw the punch from the sheet material and to return the punch to a position generally in alignment with the first die cavity; and means for holding said pad in clamping engagement with the sheet material during the return movement of the punch and punchholder. 6. A method of performing work operations on sheet material comprising:

providing a first die member at a station; holding the sheet material with at least a first section of the sheet material being at said first station; relatively advancing a tool and said first die member to perform a first work operation on said first section of sheet material with the first work operation causing the tool to become interlocked with the first section of sheet materia1; releasing the sheet material so that the first section can be moved away from the first station; moving the tool away from the first station to a predetermined location to thereby transfer said first section of sheet material from the first station to the predetermined location and to bring a second section of the sheet material to said first station; and providing a second die member at said predetermined location and performing a second work operation on said first section of sheet material utilizing said tool and said second die member. 7. A method as defined in claim 6 wherein the punch passes through less than 100 percent of the thickness of the sheet material.

8. A method as defined in claim 6 including substantially trapping a volume of air between said punch and the sheet material at said first die member and compressing said volume of air as a result of said step of relatively advancing with the compression of the air being sufficient to materially assist in the formation of said aperture.

9. A machine for performing a work operation on sheet material comprising:

a tool member operable at a first station; means for mounting said tool member at said first station for movement generally toward and away from the sheet material at the first station; means for holding the sheet material in position during at least a portion of the operation of said tool member at said first station, said last mentioned means including a pressure pad member and means for moving said pressure pad member generally toward and away from the sheet material to thereby permit said pressure pad member to selectively grip and release the sheet material;

at least one of said members being capable of forming adriving connection with the sheet material sufiicient to move the sheet material in a predetermined direction to bring a different region of the sheet material to said first station;

means for moving said one member in said predetermined direction from an initial position to a second position when said one member is drivingly connected to said sheet material to thereby move said different region of sheet material to said first station;

means for releasing said driving connection;

means for returning said one member from said second position to said initial position when there is no driving connection between said one member and said sheet material whereby said one member can progressively shuttle the sheet material through said first station;

said means for mounting said tool member including a platen and a punchholder releasably mounted on said platen, said tool member including inner and outer telescoping elements defining inner and outer working surfaces, respectively, said inner element projecting beyond said outer working surface a predetermined distance and tenninating in said inner working surface; and

means responsive to inverting of said punchholder when the punchholder is removed from said platen for withdrawing the inner working surface toward the outer working surface.

10. A machine as defined in claim 5 wherein said punch includes inner and outer members with the inner member telescoped within the outer member, said inner and outer members defining said tip portion and said second portion, respectively.

11. A method of performing work operations on sheet material comprising:

providing a first and second die portions at first and second stations, respectively;

holding the sheet material with at least a first section of the sheet material being at said first station;

providing a punch including innerand outer telescoping members defining, respectively, a tip portion and a working face, said telescoping members being arrangeable so that the tip portion projects axially of said working face and so that the working face substantially circumscribes the tip portion;

relatively advancing at least said tip portion of said punch and said first die portion to form an aperture in said first section of sheet material with the tip portion becoming interlocked with the first section of sheet material;

releasing the sheet material so that the first section can be moved away from the first station;

moving the punch toward the second station with the tip portion in the aperture to thereby transfer said first section of sheet material from the first station to the second station and to bring a second section of the sheet material to said first station; and

relatively advancing at least said working face of said punch and the second die portion to blank out the region of the sheet material which contains said aperture.

12. A method as defined in claim 11 wherein the first mentioned step of relatively advancing includes relatively advancing the tip portion and the working face toward the first die portion.

13. A press for performing a work operation on sheet material and for advancing the sheet material through the press comprising:

a platen adapted to carry a tool;

first and second platen posts attached to and projecting downwardly of said platen;

means for mounting said platen posts for movement along a generally vertical path and for movement generally transverse to the vertical path;

means for moving the platen generally along said vertical path toward and away from the sheet material at a first station, movement of the platen toward the sheet material causing the tool to perform a work operation on the sheet material at said first station and to become interlocked therewith;

a can'iage beneath said work station;

means for supporting said carriage for movement along a second path which is generally u-ansverse to said vertical P means for moving said carriage along said second path; and

said platen posts being drivingly connected to said carriage to cause movement of said platen with said carriage along said second path to thereby permit said tool to advance the sheet material a predetermined amount through the work station by virtue of the tool being interlocked with the sheet material.

14. A press as defined in claim 13 wherein said platen posts are slidably received in said carriage.

15. A press as defined in claim 13 wherein said means for moving said platen along said vertical path includes a pivotal arm drivingly connected to said posts and a cam for pivoting said arm to move the platen posts generally along said vertical path.

16. A press as defined in claim 13 including means including an eccentric bushing for adjusting the vertical stroke of the platen.

17. A press having tool means for performing a work operation on sheet material comprising:

means defining a surface for supporting the sheet material;

a pad mounted for movement toward and away from said surface to clamp the sheet material against said surface;

first and second cams;

a shaft for mounting said cams;

means for supporting said shaft for rotational and generally axial movement;

a drive motor drivingly connected to said shaft to rotate said shaft and said cams;

means for drivingly connecting said that cam and the tool means and responsive to rotation of the first cam to permit the first cam to drive the tool means to perform a work operation on the sheet material, such work operation causing at least a portion of the tool means to interlock with the sheet material;

means for moving at least said portion of the tool means laterally while said portion of the tool means is interlocked with the sheet material to index the sheet material;

means for drivingly connecting the second cam and the pad and responsive to rotation of the second cam to permit the second cam to control the clamping and unclamping of the sheet material;

a hand operated element connected to said shaft and rotatable therewith; and

means responsive to generally axial movement of said shaft to disconnect the driving connection between the motor and said shaft whereby said hand operated element can rotate said shaft and said cams independently of said motor.

l III I 

1. A method of performing work operations on sheet material comprising: providing a first die member at a station; holding the sheet material with at least a first section of the sheet material being at said first station; relatively advancing a tool and said first die member to perform a first work operation on said first section of sheet material with the first work operation causing the tool to become interlocked with the first section of sheet material; releasing the sheet material so that the first section can be moved away from the first station; moving the tool away from the first station to a predetermined location to thereby transfer said first section of sheet material from the first station to the predetermined location and to bring a second section of the sheet material to said first station; said tool including a punch and said step of relatively advancing causing the punch to enter said first section of sheet material and cooperate with said first die member to pierce an aperture in the first section of sheet material, said punch cooperating with the surface of the sheet material defining said aperture to transfer said section of sheet material to the predetermined location during said step of moving; and providing a second die member at said predetermined location, said punch having a first portion of a predetermined cross sectional area and a second portion of greater cross sectional area, said first and second portions being cooperable with said first and second die members, respectively, said second die member and said second portion of said punch blanking out said first section of sheet material to thereby form an apertured member of sheet material.
 2. A method as defined in claim 1 including relatively advancing said punch and die with sufficient speed to pierce an aperture in said first section of said sheet material without causing the punch to enter said die member.
 3. A method of fabricating an apertured member from sheet material comprising: providing first and second stations; providing a first tool at said first station; holding the sheet material with at least a portion thereof being generally in registry with said first tool; relatively advancing a second tool and said first tool in direction generally transverse to the plane of the sheet material at said first station to cause said tools to deform the sheet material into interlocking engagement with the second tool; moving the second tool from said first station to said second station with the second tool moving the sheet material therewith; performing a second work operation on the sheet material at said second station; withdrawing said second tool from its interlocking association with the sheet material; and returning the second tool to the first station.
 4. A method as defined in claim 3 wherein said second work operation is carried out utilizing said second tool.
 5. A machine for performing work operations on sheet material comprising: a supporting structure; a die on said supporting structure and having first and second die cavities at first and second stations, respectively, the sheet material being positionable to confront the die cavities; a punch having a tip portion and a second portion; means including a punchholder for mounting said punch for movement toward and away from said die and in both directions between said stations; means including a pad mounted for movement generally toward and away from the sheet material for clamping the sheet material; means for moving said pad to effect clamping of the sheet material; means for moving said punchholder and said punch toward said first die cavity with the tip portion of the punch engaging the sheet material to perform a first work operation thereon, the tip portion of the punch entering the sheet material and interlocking therewith; means for moving the pad away from the sheet material to thereby release the sheet material for movement with said punch when the punch is interlocked with the sheet material; means for moving the punchholder and the punch from said first station to said second station with the punch interlocked with the sheet material to thereby move a section of the sheet material from the first station to the second station and to generally align the punch with the second die cavity; means for moving the pad toward the sheet material to clamp the sheet material when the punch is at said second station; means for advancing the punch toward said second die cavity to cause the second portion of the punch to cooperate with the second die cavity and perform a second work operation on the sheet material; means for moving the punchholder to withdraw the punch from the sheet material and to return the punch to a position generally in alignment with the first die cavity; and means for holding said pad in clamping engagement with the sheet material during the return movement of the punch and punchholder.
 6. A method of performing work operations on sheet material comprising: providing a first die member at a station; holding the sheet material with at least a first section of the sheet material being at said first station; relatively advancing a tool and said first die member to perform a first work operation on said first section of sheet material with the first work operation causing the tool to become interlocked with the first section of sheet material; releasing the sheet material so that the first section can be moved away from the first station; moving the tool away from the first station to a predetermined location to thereby transfer said first section of sheet material from the first station to the predetermined location and to bring a second section of the sheet material to said first station; and providing a second die member at said predetermined location and performing a second work operation on said first section of sheet material utilizing said tool and said second die member.
 7. A method as defined in claim 6 wherein the punch passes through less than 100 percent of the thickness of the sheet material.
 8. A method as defined in claim 6 including substantially trapping a volume of air between said punch and the sheet material at said first die member and compressing said volume of air as a result of said step of relatively advancing with the compression of the air being sufficient to materially assist in the formation of said aperture.
 9. A machine for performing a work operation on sheet material comprising: a tool member operable at a first station; means for mounting said tool member at said first station for movement generally toward and away from the sheet material at the first station; means for holding the sheet material in position during at least a portion of the operation of said tool member at said first station, said last mentioned means including a pressure pad member and means for moving said pressure pad member generally toward and away from the sheet material to thereby permit said pressure pad member to selectively grip and release the sheet material; at least one of said members being capable of forming a driving connection with the sheet material sufficient to move the sheet material in a predetermined direction to bring a different region of the sheet material to said first station; means for moving said one member in said predetermined direction from an initial position to a second position when said one member is drivingly connected to said sheet material to thereby move said different region of sheet material to said first station; means for releasing said driving connection; means for returning said one member from said second position to said initial position when there is no driving connection between said one member and said sheet material whereby said one member can progressively shuttle the sheet material through said first station; said means for mounting said tool member including a platen and a punchholder releasably mounted on said platen, said tool member including inner and outer telescoping elements defining inner and outer working surfaces, respectively, said inner element projecting beyond said outer working surface a predetermined distance and terminating in said inner working surface; and means responsive to inverting of said punchholder when the punchholder is removed from said platen for witHdrawing the inner working surface toward the outer working surface.
 10. A machine as defined in claim 5 wherein said punch includes inner and outer members with the inner member telescoped within the outer member, said inner and outer members defining said tip portion and said second portion, respectively.
 11. A method of performing work operations on sheet material comprising: providing a first and second die portions at first and second stations, respectively; holding the sheet material with at least a first section of the sheet material being at said first station; providing a punch including inner and outer telescoping members defining, respectively, a tip portion and a working face, said telescoping members being arrangeable so that the tip portion projects axially of said working face and so that the working face substantially circumscribes the tip portion; relatively advancing at least said tip portion of said punch and said first die portion to form an aperture in said first section of sheet material with the tip portion becoming interlocked with the first section of sheet material; releasing the sheet material so that the first section can be moved away from the first station; moving the punch toward the second station with the tip portion in the aperture to thereby transfer said first section of sheet material from the first station to the second station and to bring a second section of the sheet material to said first station; and relatively advancing at least said working face of said punch and the second die portion to blank out the region of the sheet material which contains said aperture.
 12. A method as defined in claim 11 wherein the first mentioned step of relatively advancing includes relatively advancing the tip portion and the working face toward the first die portion.
 13. A press for performing a work operation on sheet material and for advancing the sheet material through the press comprising: a platen adapted to carry a tool; first and second platen posts attached to and projecting downwardly of said platen; means for mounting said platen posts for movement along a generally vertical path and for movement generally transverse to the vertical path; means for moving the platen generally along said vertical path toward and away from the sheet material at a first station, movement of the platen toward the sheet material causing the tool to perform a work operation on the sheet material at said first station and to become interlocked therewith; a carriage beneath said work station; means for supporting said carriage for movement along a second path which is generally transverse to said vertical path; means for moving said carriage along said second path; and said platen posts being drivingly connected to said carriage to cause movement of said platen with said carriage along said second path to thereby permit said tool to advance the sheet material a predetermined amount through the work station by virtue of the tool being interlocked with the sheet material.
 14. A press as defined in claim 13 wherein said platen posts are slidably received in said carriage.
 15. A press as defined in claim 13 wherein said means for moving said platen along said vertical path includes a pivotal arm drivingly connected to said posts and a cam for pivoting said arm to move the platen posts generally along said vertical path.
 16. A press as defined in claim 13 including means including an eccentric bushing for adjusting the vertical stroke of the platen.
 17. A press having tool means for performing a work operation on sheet material comprising: means defining a surface for supporting the sheet material; a pad mounted for movement toward and away from said surface to clamp the sheet material against said surface; first and second cams; a shaft for mounting said cams; means for supporting said shaft for rotational and generally axial movement; a drive motor drivingly connected to said shaft to rotate said shaft and said cams; means for drivingly connecting said first cam and the tool means and responsive to rotation of the first cam to permit the first cam to drive the tool means to perform a work operation on the sheet material, such work operation causing at least a portion of the tool means to interlock with the sheet material; means for moving at least said portion of the tool means laterally while said portion of the tool means is interlocked with the sheet material to index the sheet material; means for drivingly connecting the second cam and the pad and responsive to rotation of the second cam to permit the second cam to control the clamping and unclamping of the sheet material; a hand operated element connected to said shaft and rotatable therewith; and means responsive to generally axial movement of said shaft to disconnect the driving connection between the motor and said shaft whereby said hand operated element can rotate said shaft and said cams independently of said motor. 